Can you give a dog too much glucosamine?

We give our dogs (two german shepherds) cosequin ds. We've given our older female the same amount for quite a while and have noticed an improvement. We just increased our males to the same amount, but haven't seen the improvement and in fact have noticed he's limping a little more when he gets up (he walks it off in time). It may just be coincidental w/ our recent move and the fact that most of the floor is tile (no cushion :o)).
Thanks in advance for any advice.
We just want to be sure the increased glucosamine won't hurt our male.

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Answers

You need to check with vet:)
Things in large amounts are never good.
Also are the dogs old?
Large breeds are prone to HD and elbow problems.
If the arthritis is the problem the vet has pain meds for certain pain.